First aid is the provision of immediate care to a victim with an injury or illness, usually effected by a lay person, and performed within a limited skill range. First aid is normally performed until the injury or illness is satisfactorily dealt with (such as in the case of small cuts, minor bruises, and blisters) or until the next level of care, such as a paramedic or doctor, arrives. First aid may help the person to survive till the docter comes and saves his/her life.

The nature of first aid means that most people will only have a limited knowledge, and in emergency situations, first aiders are advised to FIRST seek professional help. This is done by calling, or assigning an able bystander to call, an emergency number, which is 9-1-1 in many places. There is no worldwide common emergency number. The European Union has established 1-1-2 as the universal emergency number for all its member states. The GSM mobile phone standard designates 1-1-2 as an emergency number, so it will work on GSM systems to contact help, even in North America. In the United Kingdom and Republic of Ireland, the numbers 999, 112 and 911 all work in parallel. In emergency situations, it is important that the responder seek help immediately, seeking professional help by other means, if telephone contact is unavailable. The risks of inadvertently doing further injury to a victim, and/or the responder sustaining injury themselves while applying aid, can often outweigh the benefits of applying immediate treatment.